New Gene Therapy Technique On Induced Pluripotent Stem Cells Holds Promise In Treating Immune System Disease

Researchers have developed an effective technique that uses gene therapy on stem cells to correct chronic granulomatous disease (CGD) in cell culture, which could eventually serve as a treatment for this rare, inherited immune disorder, according to a study published in Blood, the Journal of the American Society of Hematology.

CGD prevents neutrophils, a type of white blood cell of the immune system, from making hydrogen peroxide, an essential defense against life-threatening bacterial and fungal infections. Most cases of CGD are a result of a mutation on the X chromosome, a type of CGD that is called "X-linked" (X-CGD).

While antibiotics can treat infections caused by X-CGD, they do not cure the disease itself. Patients with X-CGD can be cured with a hematopoietic stem cell (HSC) transplant from healthy bone marrow; however, finding a compatible donor is difficult. Even with a suitable donor, patients are at risk of developing graft-versus-host disease (GVHD), a serious and often deadly post-transplant complication that occurs when newly transplanted donor cells recognize a recipient's own cells as foreign and attack the patient's body.

Another treatment option under development for X-CGD is gene therapy, a technique for correcting defective genes responsible for disease development that involves manipulation of genetic material within an individual's blood-forming stem cells using genetically engineered viruses. However, this gene therapy has so far proved to be inefficient at correcting X-CGD. In addition, these engineered viruses insert new genetic material at random locations in the blood-forming stem cell genome, putting patients at significantly higher risk for developing genetic mutations that may eventually lead to serious blood disorders, including blood cancer.

In order to develop a more effective and safer gene therapy for X-CGD, researchers from the National Institute of Allergy and Infectious Disease (NIAID) at the National Institutes of Health (NIH) and The Johns Hopkins University School of Medicine embarked on a study using a more precise method for performing gene therapy that did not use viruses for the gene correction. Researchers removed adult stem cells from the bone marrow of a patient with X-CGD and genetically reprogrammed them to become induced pluripotent stem cells (iPS cells). Like embryonic stem cells, these patient-specific iPS cells can be grown and manipulated indefinitely in culture while retaining their capacity to differentiate into any cell type of the body, including HSCs.

"HSCs that are derived from gene corrected iPS cells are tissue-compatible with the patient and may create a way for the patient's own cells to be used in a transplant to cure the disease, removing the risk of GVHD or the need to find a compatible donor," said Harry L. Malech, MD, senior study author, Chief of the Laboratory of Host Defenses and Head of the Genetic Immunotherapy Section of NIAID at the NIH. "However, turning iPS cells into a large number of HSCs that are efficently transplantable remains technically difficult; therefore, our study aimed at demonstrating that it is possible to differentiate gene corrected iPS cells into a large number of corrected neutrophils. These corrected neutrophils, grown in culture, are tissue-compatible with the patient and may be used to manage the life-threatening infections that are caused by the disease."

Typically, iPS cells from a patient with an inherited disorder do not express disease traits, despite the fact that the iPS cell genome contains the expected mutation. The researchers were able to prove, in culture, that iPS cells from a patient with X-CGD could be differentiated into mature neutrophils that failed to produce hydrogen peroxide, thus expressing the disease trait. This is the first study in which the disease phenotype has been reproduced in neutrophils differentiated from X-CGD patient-specific iPS cells.

After discovering that the disease could be reproduced in cell culture, the researchers then sought to correct the disease and produce healthy neutrophils in culture. They used synthetic proteins called zinc finger nucleases (ZFNs) to target a corrective gene at a specifically defined location in the genome of the X-CGD iPS cells. The iPS cells were then carefully screened to identify those containing a single copy of the corrective gene properly inserted only at the safe site. The researchers observed that some of the gene-corrected iPS cells could differentiate into neutrophils that produced normal levels of hydrogen peroxide, effectively "correcting" the disease.

"This is the first study that uses ZFNs in specific targeting gene transfer to correct X-CGD," said Dr. Malech. "Demonstrating that this approach to gene therapy works with a single-gene disease such as X-CGD means that the results from our study offer not only a potential treatment for this disease, but more importantly, a technique by which other single-gene diseases can be corrected using specifically targeted gene therapy on iPS cells."

Source:
American Society of Hematology

GIS Scientists Propose A New Paradigm For Embryonic Stem Cells, Potentially Speeding Up Development Of Disease Therapies

Scientists from the Genome Institute of Singapore (GIS) have put forward a novel explanation for the pluripotency[1] of embryonic stem (ES) cells. Their groundbreaking explanation opens new doors for understanding how stem cells create specific cell types, fundamental knowledge that will drive changes and improvements in the therapeutic and translational usage of stem cells. A better understanding of ES cells could help advance the development of treatments for diseases such as diabetes, Parkinson's disease, and Huntington's disease. The work, published in the journal Cell Stem Cell, was led by Dr Bing Lim, Senior Group Leader of the Stem Cell and Developmental Biology department at the GIS, and Kyle Loh, GIS student from Dr Lim's lab.

By re-examining current data with a fresh eye, Lim and Loh were able to suggest a novel paradigm that may resolve the 30-year-old mystery behind pluripotency. The prevailing model of stem cell pluripotency suggests that stem cell genes active in ES cells prevent these stem cells from turning into specific cell types. This model accounts for how ES cells can remain undifferentiated, but is unable to explain convincingly the ability of stem cells to create any bodily cell type. Lim and Loh suggest that, contrary to current thinking, individual stem cell genes do not completely suppress differentiation, but instead actively direct ES cells to produce particular bodily cell types. In their new paradigm, Lim and Loh propose that the activation of a combination of such stem cell genes within ES cells is what enables ES cells to create any bodily cell type.

[1] Pluripotency refers to the ability of ES cells to differentiate into all bodily cell types. ES cells can potentially create, on demand, any cell type that clinicians or scientists need for therapeutic, biotechnological, or research purposes. Hence, the cells are currently used as a source of specialized cell types used in cell replacement therapies. An understanding of how ES cells are able to produce all these cell types is of intense pragmatic and theoretical interest.

Source
Genome Institute of Singapore

Stem Cells Implicated In The Cause Of Bowel Cancer May Also Be Useful In Treating The Disease

Editor's Choice

Stem cells in the intestine, which when they mutate can lead to bowel cancers, might also be grown into transplant tissues to combat the effects of those same cancers, the UK National Stem Cell Network (UKNSCN) annual science meeting heard.

Professor Nick Barker of the Institute of Medical Biology in Singapore will explain how he and his team identified that the stem cells which are crucial to maintaining a healthy intestine are also the site at which bowel cancers first begin, and how he also hopes to use healthy stem cells to regenerate tissues to help patients with Crohn's disease and some cancers.

Having discovered a gene that is only turned on in these particular stem cells Professor Barker and his team have been able to isolate the cells in mice and grow small pieces of intestine in the lab. The researchers hope that if they are able to grow larger pieces, they will be able to produce transplant tissues to replace damaged intestines.

Professor Barker explains: "Processing our dinner every day is a tough job so the lining of our intestines quickly get worn out. To keep the intestine working stem cells in little pockets along the surface replace the lining, cell by cell, about once a week.

"We already knew these stem cells existed for a while we didn't know much about them because it was difficult to distinguish them from all of the other types of cells in our intestines. Our team was able to single them out and study them because we discovered a gene that is only turned on in these particular stem cells."

Once the researchers had found this gene they were able to track where the stem cells occur throughout the body finding that, as well as the intestine, the stomach lining and in hair follicles, the cells were also present in bowel tumours.

Professor Barker continues: "We hope that studying these stem cells will be doubly useful: One day we hope to grow large enough pieces in the lab to form replacement tissues for transplant; and by studying the cells we will be able to find new ways to prevent them from mutating and hence leading to cancer.

"Bowel cancer is the third most common type of cancer in England and an estimated 38,000 new cases are diagnosed each year. We know these stem cells are both implicated in causing the cancer but that they also could be useful for treating disease so we hope that studying them will help us to understand how to attack the disease on two fronts.

Source: Biotechnology and Biological Sciences Research Council

Copyright: Medical News Today

Clinical Trial Success For Crohn's Disease Cell Therapy

Speaking at the UK National Stem Cell Network annual science meeting, Professor Miguel Forte described research into a new cell therapy for chronic inflammatory conditions such as Crohn's disease. Patient's own blood cells are used to produce a type of cell - Type 1 T regulatory lymphocyte - that can reduce the extent of the disease.

Professor Forte said "T regulatory lymphocytes are amazing cells - they secrete proteins - cytokines - that dampen down the over active immune response that causes the terrible symptoms of chronic inflammatory diseases such as Crohn's. We know that treatments based on these cells can work but the challenge is to develop them in the clinic so as to maximise the benefits and minimise the risk. We must show that these cells are well tolerated and do a good job to treat the disease."

Professor Forte and his colleagues at TxCell in Valbonne, France, have used patient's own immune system cells derived from PBMCs - a type of blood cell - to treat patients with chronic inflammatory diseases like Crohn's disease. They used these cells, from patients with Crohn's, who had previously been treated with drugs and/or surgery but still had significant symptoms due to treatment resistance to make Type 1 regulatory T lymphocytes, which were then given back to the patients. The purpose of the study was to assess how well patients react in general to the treatment and also to check the efficacy of these cells for treating Crohn's disease. The preliminary results presented today show a good tolerability and, when given the correct dose, patients with severe Crohn's disease that do not respond to other treatments have an improvement in their condition.

Cell therapy approaches, like this one and also MSCs, aim at using living cells as innovative new treatments to address unmet medical needs.

Professor Forte continued "It's still early days but the preliminary results are really good. The treatment didn't make the patients ill in any way and there is an early indication that their Crohn's disease has improved. The next step will be to do what we call a "phase 2b" clinical trial to find out if the treatment definitely works, what types of chronic inflammatory disease it works for, more about any potential side effects and how to manage them, and to confirm our results on the best dose used."

Source:
Mike Davies
Biotechnology and Biological Sciences Research Council

 

Stem Cell Research May Lead To New Treatments For Parkinson's Disease, Huntington's Disease, Multiple Sclerosis, Stroke, Spinal Cord Injury

Main Category: Parkinson's Disease
A group of scientists at Marshall University is conducting research that may someday lead to new treatments for repair of the central nervous system.

Dr. Elmer M. Price, who heads the research team and is chairman of Marshall's Department of Biological Sciences, said his group has identified and analyzed unique adult animal stem cells that can turn into neurons.

Price said the neurons they found appear to have many of the qualities desired for cells being used in development of therapies for slowly progressing, degenerative conditions like Parkinson's disease, Huntington's disease and multiple sclerosis, and for damage due to stroke or spinal cord injury.

According to Price, what makes the discovery especially interesting is that the source of these neural stem cells is adult blood, a readily available and safe source. Unlike embryonic stem cells, which have a tendency to cause cancer when transplanted for therapy, adult stems like those identified in Price's lab are found in the bodies of all living animals and do not appear to be carcinogenic.

"Neural stem cells are usually found in specific regions of the brain, but our observation of neural-like stem cells in blood raises the potential that this may prove to be a source of cells for therapies aimed at neurological disorders," Price added.

So far, the group at Marshall has been able to isolate the unique neural cells from pig blood. Price said pigs are often used as models of human diseases due to their anatomical and physiological similarities to humans. In the future, his lab will work to isolate similar cells from human blood, paving the way for patients to perhaps one day be treated with stem cells derived from their own blood.

The team's research was published in a recent issue of the Journal of Cellular Physiology. The lead author of the article is Dr. Nadja Spitzer, a research associate in Price's lab. Other contributors include Dr. Lawrence M. Grover, associate professor of pharmacology, physiology and toxicology at Marshall's Joan C. Edwards School of Medicine; and Gregory S. Sammons and Heather M. Butts, who were both undergraduate students when the research was conducted.

The study was supported with funding from the National Science Foundation's Experimental Program to Stimulate Competitive Research (EPSCoR) and the National Institutes of Health.

Source:
Ginny Painter
Marshall University Research Corporation